Swing position recognition and reinforcement

ABSTRACT

A method and device is used to teach and simulate swing mechanics. A camera is coupled to a computer such that frames including an image of a golfer swinging a golf club may be captured. A key part of the image is identified by the computer in sequential frames captured from the camera, and the image is compared to swing mechanics of a known standard golfer. The position of the known standard golfer is capable of following the natural swing of a student golfer, and the method and device are capable of providing real-time feedback to the student golfer during the golfer&#39;s swing. An instant replay may be used to reinforce good swing mechanics. A marker attachment may be used to assist in tracking and analyzing the swing mechanics of the images. Parameters relating to club angle and apparent club length may be compared to a known standard for a plurality of reference swing positions in order to determine the swing mechanics of the student golfer during practice instruction and within a golf simulation game to determine ball trajectory. A ball launch monitor may be integrated with the image analysis, which improves the effectiveness of the method and device synergistically.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S.application Ser. No. 10/345,651, filed Jan. 17, 2003, now abandoned infavor of this application, which is incorporated herein by reference inits entirety, which is a continuation-in-part application of U.S.application Ser. No. 09/878,447 filed on Jun. 11, 2001, now issued asU.S. Pat. No. 6,533,675.

FIELD OF THE INVENTION

The field relates to golf instruction and golf simulators.

BACKGROUND AND DESCRIPTION OF PRIOR ART

A golf swing requires the synchronized actions of more than 80 differentmuscles in a way that is not particularly intuitive or consistent withthe human framework. Focusing on the totality of these various musclemovements surpasses the ability of the conscious mind. This requirementfor complex and unnatural muscle movements is the principle reason whygolf is considered to be a difficult game to master. Even if one issuccessful in correctly emulating the precise body movements of a givenprofessional, it is unclear that the club movements that are actuallyproduced are correct for a particular person given his or her physicaldifferences.

Correct movement of the golf club is the main objective of a golf swing.If the club moves correctly then learning the associated body movementsbecomes a far easier goal. There are as many swing styles as there arebody sizes and shapes, even among professionals, but the objective ofeach is to move the club in a very similar way.

Training tools exist that focus on body movements during the golf swing,but none describes or teaches correct club movement in terms ofgeometric position of the golf club, club head rotation and threedimensional shaft direction at every point of the golf swing. And noneperforms computer image recognition of the golf club and body positionto guide the club movements, analyze the swing and predict the ballflight.

U.S. Pat. No. 6,159,016 compares video recordings of the body motions ofa student to that of an instructor or professional. But these recordingslack interactivity because it is only after the student has completedthe exercise that he or she can view comparisons. The computers involvedreceive and display images but do not recognize or analyze club or bodymovements. That task is left to the student and/or his or herinstructor.

U.S. Pat. No. 6,126,449 allows a student to swing a club within a bodytemplate image of a chosen professional instructor. The computerreceives and displays images but does not recognize the student's actualclub or body movements, leaving the entire burden of swing analysis tothe student and his or her instructor. Because the golf swing analyzerhas no awareness of what the student is actually doing once the templateis set in motion, there can be no responsive interaction between thestudent and the device. No effort is made by the above cited patent tosystematically describe correct body position as a function of correctgolf club movement. Since the motion template of U.S. Pat. No. 6,126,449progresses through the swing unconditionally in a constant predeterminedmotion without the benefit of position recognition, the student has noopportunity to initiate motion with position reinforcement beingprovided by an intelligent process. This invention can neither analyze agolfer's swing nor predict his or her ball flight, nor display a cutoutof the golfer's image as he swings on a golf course background.

U.S. Pat. No. 6,126,449 also requires the student to synchronize his orher activities to the timing provided by the pre-recorded template. Thestudent cannot test or exercise his or her club movements swingingfreely back and forth using variable timing as he or she can with swingposition recognition and reinforcement.

In the above noted patent there is an uncertain task in deciding whichprofessional's templates to use. Then attempting to emulate the complexbody movements executed by that professional can be very difficult andperhaps of no particular advantage in achieving the club and bodymovements that are correct for the student, given the physicaldifferences between the student and the professional such as differencesin anatomy, physiology, flexibility, and strength

U.S. Pat. No. 6,059,668 teaches the effects of club movement by allowingthe student to observe a light that shines in both directions along theclub shaft generated by a device attached to the golf club shaft. Thismethod does not help the student to know if the geometric location ofthe club is correct at any point. This method fails to detect verycommon problems, such as that of the golfer bending his forward armduring the back swing producing a swing whose arc is too narrow yet ableto satisfy criteria indicating that the swing is correct.

With nothing other than a light beam to communicate to the student, theabove cited patent lacks the effectiveness and accuracy of imageanalysis and video presentation. It suffers from not being able toreview the analysis of a given swing many times at different speeds.This invention becomes the least effective during the forward swingbefore impact while the club is making its most rapid movement. Duringthis time the student must interpret the light signals and switch his orher view from the light pointing toward the grip end of the club to thatpointing toward the head of the club. This invention is unusableoutdoors under bright sunlight and physical adjustments are necessary tothe platform that reflects the beam of light when using clubs ofdifferent lengths.

U.S. Pat. No. 5,772,449 discloses a method for simulating a golfer'sswing by a two step process that first collects data about a golfer'sclub and body movements and then feeds the data to a commerciallyavailable mechanical simulation package. In the second step, an androidcomputer model attempts to reproduce the golfer's swing for the primarypurpose of determining what kinds of clubs are best suited to thatgolfer. This method is not interactive with the golfer and does notteach or include a pattern of an ideal golf swing as is explained below.

Prior inventions have used video recordings of the golf swings ofvarious professional golfers for comparison to a student as though theywere magic formulas. In fact, many professionals owe their success moreto extensive practice than to excellent techniques. Since golftournaments can be seen on national television every weekend, most ofthe techniques that amateur golfers would like to learn have becomecommon knowledge and are practiced by most professionals. What is neededis a systematic and effective way to learn and practice these well-knownclub and body movements. These techniques can be interactively taught bya software program that is capable of running on most personal computersequipped with an inexpensive video camera such as a USB web cam.

Thus a longstanding and unresolved need exists for an easy to use andinexpensive training system that allows a student to focus precisely onclub position and club movement with real-time interactive assistance. Afurther need exists for analysis while practicing back and forth swingswith no predetermined timing. The student should be able tospontaneously perform a sequence of swings without prior planning orsetup. For a proficient and experienced golfer, this capability provideseffective audio and video feedback during warm-up exercises.

Previous inventions do not have the benefit of the computerinstantaneously recognizing, analyzing, understanding and responding tothe motion of the student's golf club and reinforcing the club and bodypositions. While simulation based on analyzing the flight of the ball iseffective in determining the ball flight, such simulation is ineffectivein correcting a student golfer's swing mechanics. Even experience golfpros have great difficulty in determining and explaining the exact causeof a student golfer's poor swing mechanics. A video camera may be usedto analyze the golf swing, but a student golfer has a hard timeunderstanding what a correct swing should look like. Known swinganalyzers require the student golfer to pace his or her swing to amoving image of a golf pro. This artificial and unnatural pacing of thestudent golfer causes subtle changes in the swing mechanics, which arenot repeated when the student golfer swings at his or her own pace.Thus, there is a longstanding need for an image analysis system thatfollows the student golfer rather than the student golfer following thepace of the swing analyzer.

SUMMARY AND OBJECTS OF THE INVENTION

A golf swing training method and apparatus analyzes the image of astudent golfer and matches certain parameters of the swing to determinethe swing mechanics of the student golfer. The parameters may be used toprovide reinforcing feedback, such as visual and audible feedback to thestudent golfer, as the student golfer is practicing the student golfer'sswing mechanics at the student golfer's own pace. The parameters may beused to accurately predict the flight path of the ball by determiningclub head speed, direction and rotation during the swing and at impactwith the ball. In one example, the parameters are coupled with a simplelaunch monitor to determine the flight path of the ball, which allows asmall, inexpensive camera to be attached to the computer directly.

In another example, a short club may be used in a limited area with oneor more simulated golf balls during instruction. The device is capableof teaching good swing mechanics for a club of any length. In oneexample, swing position recognition is accomplished by an attachment ofone or more colored spheres just below the grip on the club shaft. Swingposition reinforcement based upon the recognized step-by-step progressof the golf swing verifies correct body and club position during acomputer-provided lesson. Swing position recognition also allows thegolfer to watch his or her cutout images swinging at various locationson a background golf course during a simulated golf game. When thecomputer has recognized and analyzed the nature of a particular golfswing problem and its solution, then the presentation to the student ismore effective using computer generated graphics and audio methods.Since the computer's recognition software can correlate the clubposition with the position of the student's body parts, a more focusedand systematic approach can be taken by the student to learn to swingcorrectly. Receiving a quantitative rating based upon the quality of theswing movements and viewing the predicted ball flight makes learning andpracticing more enjoyable, taking the mystery out of the analysis ofgolf swing mechanics.

When the tracking process is applied to a simulated golf game, thegolfer can watch his or her own image swinging on the simulated golfcourse and then observe the ball in flight and as it lands. He or shecan then view a replay or an in depth step-by-step analysis of theprevious swing before proceeding. In one example, the flight path of thegolf ball is predicted based on the swing mechanics and/or a launchmonitor and is compared to the flight path of a virtual pro.

In one example, the parameters measure a student golfer's swingmechanics against a semi-circular back swing plane orbit that isfollowed by a circular forward swing plane orbit. The locations withinthese orbits serve as reference points for the computer to recognize thecorrect club movements and body positions that comprise the ideal golfswing. These swing plane orbits can be further differentiated todescribe swing planes with correct three dimensional angles thatcorrespond to the effective club lengths of a short, medium or longclub.

The derivation of these swing plane orbits is based upon analysis of adatabase of swing mechanics of many professional golfers. The databaseallows the correct swing to be superimposed on the student golfer'sswing at the student golfer's own pace. Since the student golfer's swingmechanics are recognized in real time, the virtual pro follows thestudent golfer rather than the other way around. This greatly improvesthe effectiveness of the analysis, because the student golfer takes anormal swing along with all of the normal mistakes.

In a synchronized, slow motion process that revealed a pattern of anideal swing mechanics common to substantially all successfulprofessional golfers, a pattern developed. The pattern showed asemi-circular swing plane orbit for the golfer's hands during the backswing and a separate circular swing plane orbit for the golfer's handsduring the forward swing. These swing plane orbits were easilyextendable to an area of the club shaft near the golfer's hands. Thechoice of the location of the club shaft near the golfer's hands as areference point was also valuable to keep the swing plane orbits assmall as possible so the video camera's recognition capabilities areoptimized by having the golfer as close to the camera as possible.

The swing plane orbits may automatically determined while the golferassumes his or her normal stance by considering the height and otherphysical characteristics of the golfer. In one example, the imageanalysis system instructs the student golfer to position the cameraaccording to these same metrics, eliminating the need for the studentgolfer to measure the distances with a tape measure or other measuringdevice.

The proper golf swing mechanics may be further reinforced by severalcalibrating movements. The swing plane orbital locations form a basisfor evaluating club shaft direction, clubface rotation and overall bodyposition during a golf swing. They form the basis for swing positionrecognition and reinforcement that displays a humanoid pattern thatrepresents the ideal club and body positions.

In one example, a marker attachment is placed on the shaft below thegolf club grip, such as an orb or a set of orbs. Preferably, thematerial and/or the external coating on the orbs is selected to have ananti-reflective surface, such that substantially no glare is perceivedby the camera from the orb or orbs. In one example, the orbs areidentifiable by different colors. The image analysis algorithms maydistinguish one orb from the other or one portion of an orb from anotherportion of the orb by the difference in color. Furthermore, blurring ofthe color may be used by the algorithms to analyze the golf swingmechanics.

The attachment may be tracked in real time by a software program thatreceives video camera images. The use of the attachment provide moreinformation with a low resolution camera and lower frame rate than ispossible with the same equipment without the attachment. For instance, atwo-colored orb having one hemisphere in one color and the otherhemisphere in another color may be used to determine club rotation. Thisallows the analyzer to determine whether the club face is open or closedat impact with the ball, which is an important parameter that is notmeasured by simple launch monitors or expensive infrared golf ballflight monitors, which cannot accurately determine ball rotation. Thesoftware program continuously monitors the position of the sphericalattachment to determine if the club is in a correct swing plane orbitallocation and compares the student golfer's swing mechanics to a virtualpro. Any recognizable patterns on the attachment may be used to analyzethe rotation of the club shaft that corresponds to the position of theclubface at a given swing plane orbit location and the direction of theclub shaft. If camera resolution and frame rate are adequate, the systemis capable of monitoring the rotation of the club head and/or the handsof the golfer. In this case, an attachment is not required, but imageanalysis techniques are used to recognize the outline of the club heador the hands and are compared with the appearance as the head and/orhands are rotated.

In one preferred embodiment, four distinct spheres are used to achievequality recognition when slow camera speed causes the swinging clubimage to streak. In the downline view that is often used by actualprofessional trainers, the position of the solid-color balls is used todetermine the club shaft's two-dimensional angle. A ball that has twodissimilarly colored hemispheres is divided in the same direction as theclub shaft and is viewed to determine club's face rotation. Another ballmay have two dissimilarly colored hemispheres divided perpendicularly tothe club shaft. This ball, the measured club length, and attachmentlocation determine the club shaft's three-dimensional angle foradherence to the ideal swing plane as the camera sees the golfer alongthe downline view.

Although the downline view is commonly used by golf pros, it isdifficult to see the body movements and swing arcs from the downlineview. In one example, a student golfer may position the camera for aface view of the student golfer. This usually feels more natural for thestudent golfer. In this case, the image analyzer is capable ofdetermining the swing plane position merely by the location of keypoints of the arms and apparent club shaft length. This provides for avery rapid determination of swing mechanics errors and real timefeedback to the student golfer even using very inexpensive equipment. Acamera and image analyzer with a frame capture rate of less than 30frames per second may be used to analyze such problems as a flat backswing and other swing mechanics. Indeed, the one-dimensional, apparentshaft length and position of the arms is able to accurately determinethe two-dimensional swing plane and three-dimensional club position.This surprising and unexpected capability allows the system resources tobe used to provide improved graphics and/or better determine rotation ofthe club in real time. Image analysis of apparent club length is easilydetermined even from grainy camera shots by measuring the length betweenthe easily recognized club head and the golfer's hands. The position ofthe golfer's hands may also be used as a key point in determining theposition of the swing. An attachment device, as discussed previously,further improves the capability of the system to analyze the swingmechanics with marginal hardware.

A conventional personal computer control interface such as a mouse orkeyboard may be used to select the analysis activities, options anddisplays. In an alternative embodiment, the golfer controls the sequenceof activities and choices during his computer lesson or golf game bymoving the club attachment as a pointer onto a selection button. Thisfeature permits the golfer to make various choices while remaining inhis or her normal stance that may be about five feet from the camera andsome distance from the display screen, keyboard and mouse. The studentcan use a separate monitor for each display or use multiple windows of amonitor capable of displaying combinations of views simultaneously thatmay show different views based upon the concurrent use of multiple videocameras.

An initial calibration may be used to adjust the camera position,lighting and position of the limited area platform for consistentongoing positioning. During and after the calibration, a light meterfeature is capable of telling the user whether the light level is dark,dim, normal or bright. The light meter reading is accomplished byexamining the brightness and gray levels of known colors of theattachment following recognition, for example, without the need for aseparate light meter attachment.

One display shows the student's image and swing plane orbits plus thecorrect club shaft direction and clubface rotation at various intervalsalong the swing plane orbital path. Another display shows a blow-up ofthe region of the spherical attachment to precisely view the student'sactual club position at that moment and the relation to the display ofthe correct club position with respect to the swing plane orbitallocation, club shaft direction and club head rotation. Body movementerrors are identified at each swing plane orbital location andillustrated suggestions for corrections are offered. Tempo of the swingis evaluated. A USGA handicap rating is assigned to the swing, the scalefor which was determined statistically by a correlation of many golfer'sactual handicaps versus their level of correctness of swing. Instantreplay of the swing can be done at regular speed or in slow motion.

Another object and advantage is to display a computer generated humanoidimage of the correct body position of the student relative to thecurrent swing plane orbital location of the club attachment. Thisprovides swing position reinforcement to help the golfer achieve correctclub and body movement. This is an ideal learning situation since thestudent golfer takes the initiative rather than being led through eachstep and receives real-time reinforcement for his motion decisions.

Another analysis activity places the golfer on a golf course or practicerange where the ball flight and distance are predicted based upon thereal-time analysis of the swing leading to and following the ball impactposition. During these activities, the golfer can see his ball in flightas it travels toward a simulated green. A replay or detailed analysiscan be viewed subsequently for any swing. An embodiment of the golfcourse and practice range activities places a cutout camera image of thegolfer onto a simulated golf course or practice range backgrounds. Thiscutout camera image corresponds to the current position of the clubattachment with respect to the ideal swing pattern. As the currentposition proceeds near the correct positions of the ideal swing pattern,the golfer can see himself or herself swing on the golf course orpractice range. In this way, the golfer can combine simulated play andswing analysis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate three different swing mechanics at the samereference position, as captured by a camera in the face on view of thegolfer.

FIGS. 2A-2C illustrate addition of a marker attachment to the club shaftof FIGS. 1A-1C.

FIGS. 3A-3C illustrate the same three swing mechanics at the samereference position as shown in FIGS. 1A-1C, as captured by a camera inthe downline view of the golfer.

FIGS. 4A-4C illustrate addition of a marker attachment to the club shaftof FIGS. 3A-3C.

FIGS. 5A-5C illustrate a method of tracking the club of the golfer andoverlaying an outline, semi-transparent image of a virtual pro on theimage of the student golfer to provide real-time feedback during a swingat the golfer's own pace.

FIG. 6A illustrates a front view of a marker attachment.

FIG. 6B illustrates a back view of a marker attachment.

FIG. 6C illustrates the marker attachment of FIGS. 6A and 6B attached toa club.

FIG. 7 illustrates a golf simulation having a virtual pro scene cut-outthat follows the image of the golfer at the golfer's own pace.

FIG. 8 illustrates a plurality of reference swing positions.

FIGS. 9A-9C illustrate a method of setting up the distance of thestudent golfer from the camera in the face on view of the studentgolfer.

FIG. 10 illustrates a short “club” for use in confined spaces having amarker attachment integrated with the short club.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

A system for improving golf swing mechanics includes a camera, acomputer coupled to the camera, and a program that analyzes the swing ofa golfer. The program may provide immediate feedback to the golfer, suchas visual and audio feedback. Audio feedback may be provided by thecomputer or a speaker attached to the computer, which provides tips forimproving the golf swing mechanics of the golfer while the golferpractices his golf swing at the golfer's own pace. Visual feedback maybe displayed on a display screen, monitor or any other viewing system,such as virtual reality headsets and the like. The viewing system iscoupled with and controlled by a computer. For example, visual feedbackshows an image or outline of a known standard, such as a golf pro or asynthesis taken from a plurality of golf pros. The image of the knownstandard may be shown in a position that corresponds to the currentreference swing position of the student golfer during the studentgolfer's swing. The current reference swing position is identified bythe system and tracked, and the image of the known standard is paced tofollow the student golfer, who merely swings at the student golfer's ownpace.

In one embodiment, the student golfer may select a specific club to usein practicing the golfer's swing. The system matches the student golferwith a known standard using the same club. In one drill, the studentgolfer selects a plurality of clubs and practical instruction isprovided with each club in sequence. By overlaying the image of a knownstandard using the same club as the student golfer over the image of thestudent golfer, without forcing the student golfer to change his or herown pace, the student golfer receives continuous feedback on swingmechanics during a practice swing. Being able to swing at the golfer'sown pace is a significant advantage, allowing the golfer to concentrateon swing mechanics and not pace. The overlayed image follows the golferand immediately shows the golfer if the golfer's swing mechanics arediverging from the known standard. In one embodiment, the student golferselects the known standard from a menu of known standards. For example,the student golfer may choose a well known pro, an actual instructor, alongest drive champion or a composite known standard based on thecombined swings of a plurality of professional golf instructors.

In one example, a camera is disposed such that a face-on view iscaptured of the golfer and the club, as shown in FIGS. 1A-1C. Thegolfer's hands, arms, or any feature of the club may be used todetermine where in the swing the golfer is during the swing. In oneexample, the image of the golfer is overlayed in real time with acorrect golf swing that most closely matches the reference swingposition of the actual, student golfer. FIGS. 1A-1C show three examplesof a golfer who is in about the same reference swing position, but eachof the three golfers has different swing mechanics. The position of thehands, the angle of an arm, the position and length of the shaft or thepoint of the golf club where the grip intersects the shaft may be usedto determine the reference swing position, which allows the computer tooverlay the golfer's image with an image of a known standard golferusing correct golf swing mechanics, such as illustrated in FIGS. 5A-5C,for example. In one preferred embodiment, the point of the golf clubwhere the grip intersects the shaft is used as a key part to determinethe reference swing position. This is readily determined from the imagesof inexpensive cameras that may be directly attached to a computer's USBport, for example. Thus, the system may be very inexpensive and may beused by average golfers or those new to the sport, which is anotheradvantage over other systems. With this tracking of the reference swingposition, an image of a virtual pro may be paced to follow the normalpace of the student golfer in real time on a display using an overlay,outline or cut-away view of the virtual pro, which may be a defaultknown standard or a known standard selected by the student golfer or atrainer assisting the student golfer. Preferably, the virtual pro isselected to suit the style of play, body build and height of the studentgolfer, for example.

The apparent distance from the grip to the club head may be determinedby the number of pixels between the key part of the club head and thekey part where the grip intersects the club shaft, for example. Thisapparent distance, normalized by the length of the club shaft in pixels,has been found to be the same for most professional golfers at about thesame reference swing positions. By apparent distance it is meant thatthe distance is measured from the image of the club. A club disposed atan angle toward or away from a camera appears shorter than the same clubdisposed perpendicular to a line drawn between the camera and the clubshaft. Thus, the apparent distance between any two points on the clubnormalized to the actual known distance between the same two pointsprovides a measure of the three-dimensional, out-of-plane angle of theclub shaft. Thus, a deviation between a known standard apparent distanceand a measured apparent distance at the same reference swing positionmay be used to immediately instruct the student golfer of a defect inthe student golfer's swing mechanics. For example, the distance inpixels of the shaft in FIG. 1A is 50% less, indicating a flat plane orflat-back swing plane. FIG. 1C illustrates a distance in pixels about50% greater, indicating an excessively steep plane. This is easilydetermined in real time during a student golfer's swing, allowingaudible feedback to inform the student of the problem and/or correctionrequired.

FIGS. 2A-2C show an example of a golf club having special markers placedon the shaft of the club. For example, a marker attachment for use inthe system is illustrated in FIGS. 6A-6C. In FIG. 2A, the golfer isswinging too flat. In FIG. 2C, the golfer is swinging to steep. In FIG.2B, the golfer is swinging just right. As can be seen from the sequence,the camera can determine the difference between a swing that is tooflat, correct and too steep merely by determining the distance betweenthe markers. If the distance between the markers is too short, then theswing is too flat. If the distance is too long, then the swing is toosteep. But, if the distance is correct, during the swing, then thegolfer is swinging in the correct swing plane.

The method of determining the correctness of a swing using a camera tocapture a face-on view of the golfer has never been used previously. Ithas been found that the system is capable of determining the correctnessof the swing plane used by the golfer merely by analyzing the length ofthe shaft. The actual length of the club shaft may be entered by thegolfer or may be imaged directly by the camera. The length of the clubshaft during the swing may be computed as a ratio of the actual shaftlength, for example. By comparing this ratio during the swing to theratio of a correctly executed swing, the program is capable of detectingimproper swing mechanics. Then, the program may provide visual or audiocues or instruction to the golfer to correct the improper swingmechanics. In one example, the apparent distance between two points onthe shaft is determined by counting the number of pixels between thecenter of mass of two key parts of the club, such as the intersection ofthe grip and the shaft, the club head or two markers attached to theclub shaft at a known spacing.

Markers are not required for analyzing the golf swing mechanics usingthis method. Even comparatively poor resolution video images, as shownin FIGS. 1A-1C may be used to determine the club shaft length bycounting the number of pixels between the golfer's hands and the clubhead, for example. In one embodiment, the golfer wears a golf glovehaving a high contrast to the background, which helps to identify thegolfer's hand. While the glove may be considered a “marker,” it is muchless noticeable to the golfer than the markers used in FIGS. 2A-2C anddoes not add any weight to the shaft of the club. Thus, the golfer ismore likely to use the same swing mechanics as during the golfer'snormal swing.

In another example, such as illustrated in FIGS. 3A-3C, a camera isdisposed in a downline view of a golfer. In a downline view, it isnecessary to analyze both the position of the hands and the angle of theshaft of the golf club in order to determine whether the golfer isswinging the club in the correct swing plane. As illustrated in FIGS.3A-3C, the angle of the club may be determined based on the position ofhands and the golf club head or by the shaft directly. Higher resolutionimages of the shaft or more complex image analysis algorithms may berequired to determine the angle of the shaft than are required in FIGS.4A-4C, when markers are used.

FIGS. 3A-4C show how the accuracy of the two-dimensional swing plane isdetermined relative to three dimensions at a given swing position for aclub shaft with a special attachment from the down-the-line or downlineview. This view is favored by many golf instructors, who are used tothis view from live lessons. At the specific reference swing positinshown in the figures, the correct radial angle A from the bottom sphereto the top sphere as shown in FIG. 4B is the known standard angledetermined from observation of many professional golfers. The flat planeimage shown in FIG. 3A has a shaft angle that is about 30 degrees in acounter clockwise direction from the preferred angle. The steep planeimage shown in FIG. 3C has a shaft angle that is about 30 degrees in aclockwise direction from the preferred angle. FIGS. 4A-4C show the samesequence, except that the marker attachment makes imaging of theposition and angle of the club shaft much easier to accomplish withoutusing image analysis techniques to capture the actual club position andangle.

Tracking

Tracking involves image recognition in each frame of the golfer'scurrent swing reference position coordinates. The swing referenceposition coordinates may be determined from one or more identifiable keyparts, as discussed previously, such as the hands, a glove, theintersection between the grip and the shaft or a marker of a markerattachment. On preferred key part is the point of the golf club wherethe grip intersects the shaft. This key part is a pivot point for wristcock and wrist release; therefore, discerning its coordinates servesmultiple purposes: identifying the reference swing position and as a keycoordinate in evaluating the student golfer's swing mechanics.

Wrist cock occurs when the shaft of the club continues clockwise motionduring backswing. Wrist release occurs during the forward swing justprior to the head of the club striking the ball. Proper wrist cock andwrist release are essential for achieving a powerful drive from the tee,for example. Metrics that determine the angle of the club of a studentgolfer compared to a known standard may be used to discern any problemswith wrist cock and wrist release, if monitored throughout the golfer'sswing.

The reference swing position coordinates are a predetermined sequentialset of image points derived from the swing of a selected virtualprofessional golfer. In one embodiment the student golfer or aninstructor chooses the virtual professional golfer. In anotherembodiment, the computer matches a virtual professional golfer havingsimilar body size, approach to the ball and stance with actual golfer.In yet another embodiment, a default standard virtual professionalgolfer is used.

In one example, the current swing position is the ordinal numbercorresponding to the reference swing position coordinates nearest thecurrent swing position coordinates. Successful recognition of swingposition coordinates may be accomplished by the identification of keyparts, such as parts of the golf club and parts of the actual golfer'sbody. For example, key golf club parts may include the grip, the shaftand/or the club head, and key body parts may include the hands, thearms, the torso, the legs and/or the head of the student golfer. Forexample, the coordinates of these key parts may be determined based onthe center of mass of pixels identified as a portion of these key parts.

In one specific example, a special club shaft attachment, as illustratedin FIG. 6, is used as a key part of the golf club. Then, the key golfclub parts may include the grip 72, the shaft 76, the club head 74 andthe special attachment 61 or only the special attachment 61 may be used.The key body parts may include only the head of the student golfer orboth the head and the center of mass of the torso, for example. In thisspecific example, a green orb nearest the grip 62, which may bespherically shaped, is compared to two additional green orbs 66, 70 at aknown distance from the first green orb 62 to yield accurate angles forwrist-cock and swing plane comparisons, as illustrated in FIGS. 2A-2Cand 4A-4C, for example. In one example, the club head 74, club grip 72and shaft 76 may be used to reinforce the probability of an accuratematch. In this example, even if any of the club head 74, club grip 72and shaft 76 position information are not captured by the system, thesystem is still capable of tracking the current swing position.

Additional orbs 64, 68 on the marker attachment device 61 are bi-coloredblue and red. It will be apparent from FIG. 6 that the two orbs 64, 68are positioned on the shaft 76, and whereas one is red on the left 69,the other is red on the right 63, as viewed from the front view of FIG.6A. One advantage of using two additional markers 64, 68 is that thecolors red and blue are not uniformly captured by the camera in alllighting conditions; however, using both of the markers 64, 68oppositely oriented in a mirror image configuration provides a reliablemeasure of the angular rotation of the club shaft 76. Determination ofrotation of the club shaft 76 may be used to determine if the club faceis open or closed upon contact with the ball, which may be used todetermine if the ball will slice or hook, for example. In oneembodiment, the image analyzer counts the number of red and blue pixelsfor each of the bi-colored orbs 64, 68. As the club shaft rotates, thenumber of red pixels and blue pixels changes for each of the orbs 64,68. It has been found that, even if the speed of the shaft and the framerate of the camera cause streaking of the image of the balls 64, 68, anaccurate count of blue and red pixels may be determined. The relativeratio of red to blue or blue to red provides a reliable measure of therotation of the shaft. Reliability is improved by having two bi-coloredballs 64, 68 having mirror imaged colors, because the effects oflighting on color saturation on the CCD is easily discerned andcorrected. For example the sum of the count for red pixels of the firstorb 64 and the count for blue pixels for the second orb 68 may becompared to the sum of the count of the blue pixels of the first ball 64and the count of the red pixels of the second ball 68, averaging out theeffects of lighting.

Identification of key golf club and body parts may begin during the“take your stance” phase of a swing or drill. When the student addressesthe ball, the generic key part descriptors are compared to each of theactual key part stance areas of each incoming image. These key partareas are a function of the golfer's height. If a sufficiently probableset of key part matches is determined in any image, the stance positioncoordinates are recognized. The actual key part descriptors areformulated and may be saved for the student golfer.

Following recognition of stance position coordinates, the student iscommanded to “begin your swing”. Each incoming image is then scanned tolocate the current swing position coordinates. The actual key partdescriptors from the last swing position coordinates match are comparedin a restricted range of the image. The range is limited by the elapsedtime since the last match and the specific part of the swing. Lessscanning range is necessary during the back swing than the forwardswing, because the club travels faster during the forward swing, usuallythree times faster.

In one example, as soon as a sufficiently probable set of key partmatches is determined in an image, the current swing positioncoordinates are determined based on reference coordinates nearest theintersection of the grip and the shaft of the student golfer's club.

Reference Swing Position Coordinates

In one example, a reference swing position is displayed as a translucentand outlined image of a selected virtual professional golfer. Thetracking system determines the reference swing position coordinates andoverlays the correct reference swing over the image of the studentgolfer. Thus, the student golfer is provided immediate visual feedbackthat compares the student golfer's swing mechanics to the correctreference swing mechanics of the virtual pro. The back swing arc isabout 180-degrees and the forward arc is approximately 360-degrees. Forexample, if the individual reference swing positions are chosen at18-degree radial intervals, then a total of 36 swing positioncoordinates, as shown in FIG. 8, may be displayed during a typical, fullgolf swing of the student golfer. FIG. 8 helps to illustrate the notionof reference swing positions. Twenty lines are shown, and three imagesare overlayed showing three different reference swing positions, at thebeginning of the forward swing, partway through the forward swing, aswrist release is commencing and during the follow-through at the end ofthe forward swing.

In another example, a reference swing position is displayed as a golfcourse scene with the outline of a selected virtual professional golfercut-out from the scene. This cut-out scene is shown in FIG. 7 overlayingthe student golfer's image. In FIG. 7, the golfer is using proper golfswing mechanics, as shown by the close fit between the golfer and theknown standard showed at the closest reference swing position.

For example, each set of reference swing position coordinates may beassociated with the correct reference swing. Values of a referenceprofessional golfer's wrist cock angle, swing arc width,three-dimensional club angle of the two-dimensional swing plane, andspine angle may be compared to the actual student golfer's swingmechanics. For example, swing arc width may be determined by countingthe number of pixels between the center of mass of one key body part,such as the torso or head, and another key part, such as the glove,intersection between the grip and the shaft or first orb of the markerattachment.

Key Parts Identifiers

Beginning at the initial stance, key part identifiers are formed byprobable matches in the image. These identifiers may be dynamicallycreated during the swing following each match for current swing positioncoordinates. The current key part identifier is used as the basis forsubsequent comparisons.

For clubs with no special attachments, key parts identifiers may containimage data and other information about the coordinates of each key part,the actual pixels of the key parts, density of the key parts, an RGBclassification of the key parts, various edge properties of the keyparts, size of the key parts and rotation of the key parts. In addition,factors that describe the way the key parts are changing with time maybe analyzed and recorded during the swing.

Use of special colored markers may allow less sophisticated imageprocessing to be used to analyze golf swing mechanic values than isrequired for images captured without the use of the markers. When amarker attachment is used, the information desired is largely the same,but the complexity in identifying the key part identifiers is reduced,because the markers, which may be spherically shaped orbs, are uniformand may have an anti-reflective surface. For example, spherically-shapedorbs do not have rotational differences or interior edges. Also,attached markers may have a color scheme and size that makes it easy toidentify and distinguish the markers from each other and from thebackground. In one example, the markers are made of a lightweight foammaterial that adds little weight to the shaft and provides ananti-reflective surface.

Real-Time Analysis

Real-time analysis allows a translucent and outlined image of a virtualpro to be overlayed on the image of the actual, student golfer. In oneexample, each successful match during the golf swing causes the image ofthe virtual pro to be advanced to the current position of the studentgolfer. For example, a large number of images of virtual pro golfers maybe pre-recorded, and one may be selected for overlay on the studentgolfer's image captured by the camera.

In one example, FIGS. 5A-5C illustrate the process of updating an imagedisplayed to the student golfer in real time, which may also be storedfor later review. The virtual pro's overlay follows the student golfer'simage captured by the camera, while the student golfer makes a swing atthe golfer's own pace based on tracking of the student golfer's image,identification of key parts and advancing of the reference swingposition coordinates.

Unlike previously known golf swing imaging systems, the student golferneed not do anything different from a normal swing. No effort orawareness by the student is necessary, and the student can proceed athis or her own timing. The student can pause, back track and proceedduring a swing motion as the virtual professional overlays continue tofollow the golfer's own movements. This facilitates analysis forfault-correcting interactive drills, which are not possible with knownsystems.

A comparison is made between the student's key parts and those of thevirtual pro at the current swing position. In one embodiment, thedeviation limits may be predetermined by the student's choice of skilllevels. If the deviation of the student's wrist-cock angle, swing planeangle or spine angle exceeds the limit, a specific swing fault may beannounced immediately. This provides the ultimate interactivity forswings and drills. The student golfer may repeatedly exercise the golfswing, making corrections until the golf swing mechanics of the studentgolfer match, within the deviation limits selected, the golf swingmechanics of the virtual pro.

In another embodiment, a replay may follow immediately after completionof the swing. In one example, the display hesitates at each swingposition where an error was announced, which allows the student golferto visualize the difference between the golfer's own image and that ofthe overlay of the virtual pro.

Fix Swine Faults

The system may provide a virtual tutor for the student golfer. Forexample, during or after the student golfer watches a replay of thestudent golfer's swing mechanics and overlay of the virtual pro, theshortcomings of the student golfer's golf swing mechanics may becritiqued both visually and audibly. Then, the program may recommend aswing mechanics drill or drills to correct the shortcomings. In oneexample, the drill or drills are shown to the student golfer insequence, and the student golfer is given an opportunity to practice thedrills. A replay of the drill followed by a still-view comparison of theoriginal fault compared to the best progress at the swing positioncorresponding to the fault may be displayed. The student golfer mayrepeat the golf swing mechanics analysis as many times as necessary tocorrect all of the shortcomings. Then, the student golfer may change thedeviation settings to continue improvement until the student golferclosely matches the desired golf swing mechanics of the selected virtualpro.

Simulation of a Golf Course Setting

In another embodiment, the student's image is displayed within theboundaries of the virtual professional's outline, bordered by a scenesuch as a golf course scene. In one example, each successful trackingmatch during the golf swing causes the virtual pro's scene cut-out imageof the virtual pro, as shown in FIG. 7 to be advanced to the currentposition of the student golfer. This allows the student to see his imagewithin that of the virtual pro as he would appear on an actual golfcourse. The image may be represented on one or more than one displayscreens. For example, display screens connected over a network or theinternet may be used to play a multi-player round of virtual golf withor without the display of the virtual pro's cut-out overlay.

The virtual pro's scene cut-out overlay follows the student golfer'simage captured by the camera, while the student golfer makes a swing atthe golfer's own pace based on tracking of the student golfer's image,identification of key parts and advancing of the reference swingposition coordinates.

A replay may follow immediately after completion of the swing. In oneexample, the display hesitates at each swing position where an error wasannounced, which allows the student golfer to visualize the differencebetween the golfer's own image and that of the scene cut-out overlay ofthe virtual pro.]

Matching the Height of the Student to the Virtual Pro

It is important for a student to match height-wise to any selectedvirtual pro, both for tracking accuracy and visual comparisons. Basedupon the specified height of the student, the student steps backward toreduce the height of his or her image or forward to increase the heightof his or her image. The image of the virtual pro is raised or loweredaccordingly, as shown in FIG. 9 to achieve height matching.

Simulated Play

In another example, the student golfer is able to play a simulatedcourse, including driving, woods, irons, chipping, hitting out ofbunkers and putting. The image analyzer provides information that is notavailable from known launch detection devices. Specifically, theeffectiveness of launch monitors for short putts is extremely poor, butthe image analyzer predicts the path for short putts very accurately.Also, the spin that is put on the ball by the club face is capable ofcausing the ball to hook or slice. If the club face is “closed” oncontact with the ball, then the ball will tend to hook (i.e. curve tothe golfer's left). If the club face is “open” on contact with the ball,then the ball will tend to slice (i.e. curve to the golfer's right).This curve depends on the spin put on the ball by rotation of the shaftduring the golfer's swing and is not accurately measured by known launchdetection devices, such as Q-Motions launch detection device. Launchdetection devices are capable of measuring the velocity of the club headand direction of the club head on contact with the ball. This providesan initial speed and direction to the golf ball's trajectory. The spinon the ball, which may cause the ball to curve during its flight in onedirection or the other, is independent of this speed and direction. Thespin is important for determining the actual course of the trajectory,as any weekend golfer knows very well. Indeed, most professional golfersstrike the ball in a direction that is a little right of their intendedtarget and rely on a slight hook to curve the ball back to the targetline.

Also, if the club head precedes the grip of the club, then the ball willtend to take a trajectory that is higher than normal for the clubselected. Ordinarily, the grip of the club slightly precedes the clubhead to a line extending upwards through the ball. However, if the gripprecedes the club head by too great of a distance, then the trajectoryof the ball will be flat compared to the trajectory that is normal forthe club selected. Known launch detection devices are not capable ofdetermining the position of the grip at the time of impact; therefore,the trajectory is based only on the velocity and direction of the clubhead and the angle of the club selected.

In one embodiment, the image analysis system is used to detect therotation of the club head and/or the position of the grip compared tothe club head, such as at the time of impact with the ball. From therotation of the club head, the rotation imparted on the ball may beaccurately determined. From the position of the grip compared to thehead, the divergence of the trajectory from the norm for the clubselected may be determined. This improves the accuracy of the predictionof the actual flight of a golf ball and provides better feedback to thegolfer. A golfer is capable of working on the golfer's hook, slice andgrip location in a more realistic setting than during drills.

In one embodiment, the image analysis system also determines thevelocity and direction of the golf head at impact with the ball. In thisembodiment, a faster frame rate is desirable in order to have moreinformation about the location of the key points during the highestvelocity portion of the golf swing. For example, 30 frames per secondmay be adequate for estimating the golf club head velocity and directionat impact with the ball. More preferably, a higher frame capture rate ischosen to increase the number of reference swing positions. In oneexample, the image of the student golfer is shown against the setting ofthe golf course. In another example, the image of the student golfer isalso overlayed with a virtual pro image. In yet another example, thestudent golfer may select to use a virtual pro's image as a sprite inthe virtual play of the game.

For example, the student golfer's image may be displayed within theoutline of a virtual pro within an imaginary or actual golf coursesetting, which may be selected by the student golfer. In one example,each successful tracking match during the golf swing causes the virtualpro's scene cut-out image of the virtual pro, as shown in FIG. 7, to beadvanced to the current position of the student golfer. This allows thestudent to see his image within that of the virtual pro as he wouldappear on the course. The virtual pro's scene cut-out overlay followsthe student golfer's image captured by the camera, while the studentgolfer makes a swing at the golfer's own pace based on tracking of thestudent golfer's image, identification of key parts and advancing of thereference swing position coordinates.

In one example, the flight of the student golfer's ball is compared tothe trajectory of the virtual pro's ball. This can clearly show theaffect of improper club rotation. For example, the trajectory of thevirtual pro's ball may be shown as a colored arc, dashed arc orotherwise highlighted trajectory, compared to the flight of the studentgolfer's ball. In this example, the system may provide audible or visualtips to the student golfer before, during and after the swing based onthe historical record maintained on the student golfer's golf swingmechanics. For example, the system may instruct the golfer to change thegolfer's stance, to modify a grip, to avoid flat back or any other tipthat might be provided by a live golf instructor.

One advantage of the image analysis system is that it captures videoimages of the student golfer that may be replayed, immediately aftercompletion of the swing in order to provide a more detailed critique ofthe swing and the resulting impact on the trajectory of the golf ball.In one example, the display hesitates at each swing position where anerror was announced, which allows the student golfer to visualize thedifference between the student golfer's own image and that of thevirtual pro.

Hardware

An image recording device, such as a video camera or other chargecoupled device, may be used to record the images. It is preferred tohave a camera capturing at least 30 frames per second. A full speed golfswing requires about 1.5 seconds of continuous recording for an ordinarygolfer; therefore, 30 frames per second is capable of yielding about 45images during a golf swing. However, the rate of the swing increases asthe club head approaches an impact with the ball. In this case, thenumber of images captured at 30 frames per second that are near theimpact with the ball are limited in number by the speed of the club.Also, if the frame rate or shutter speed of the camera is too slow, thenblurring of the images of the club may make accurate estimates of clubangles difficult. A marker attachment allows for analysis of the keypoints even at impact with the ball using a camera that captures 30frames per second.

An image should capture a full view of the student golfer and the clubthrough the entire arc of the swing. In one embodiment, a wide-anglelens provides a field of view greater than 75 degrees, allowing the fullview with a student golfer standing within 6 feet of the camera.Preferably the lighting is about 80 lux or brighter, as measured with alight meter, if a marker attachment is used. More preferably, thelighting is about 120 lux or brighter, especially if no markerattachment is being used. The camera system should include lightbalancing that eliminates glare spots.

Preferably, the camera contains at least 640×480 pixels to allow for keypart identification and measurements. For example, if the camera uses acharge coupled device (CCD), then the device may have a dimension of 1/3″. Higher resolution cameras are preferred for image analysis without amarker attachment.

It is preferred to have system memory that is capable of storing all ofthe captured frames concurrently without saving to disk. For example, if36 positions are to be captured and overlayed, then it is preferred tohave adequate system memory to operate the program, capture the 36images of the golfer and overlay the 36 images of the virtual pro. Morememory is needed if the number of the images, resolution of the imagesor size of the images is increased. It is within the skill of a normalartisan to determine the amount of memory needed to operate the systemdescribed and claimed.

Preferably, a display device is viewable from the position of thestudent golfer to provide visual feedback. A speaker or audio devicethat is capable of being heard by the student golfer may be coupled withthe computer to provide audio feedback.

Preferably, the system processor and/or graphic co-processor is capableof real-time image capture and processing. A graphics processor maycouple the computer to the display such that the student golfer iscapable of viewing the golfer's swing in real time during the swing.

In one embodiment, the student may select a specific club, and thesystem matches the known standard with the length of the club. Inanother embodiment, the student golfer uses the club as pointing todevice to request the use of a specific club. Any club may be played,including putter, wedges, irons, woods and drivers. A database for knownstandards using different clubs is used to analyze the swing mechanicsat the reference position coordintes previously described. In analternative embodiment, the “club” may be a short club that does notreach the ground. In this embodiment, the marker attachment may beattached to the club or may be integrated with the club. For example, ashort club according to this embodiment is shown in FIG. 10.

FIGS. 9A-9C illustrate one of the setup steps during setup of thesystem. A student golfer may be instructed to move the camera or theball further apart or closer together. In one embodiment, nomeasurements are required by the student golfer. For example, the systemautomatically adjusts the location of the virtual pro onto the image ofthe golfer. As shown in FIG. 9A, if the golfer is too close to thecamera, then the distance between the camera and the golfer isincreased, as shown in FIG. 9B. The outline of the virtual pro does notoverlay properly on the golfer in FIG. 9B, but the system may be capableof automatically translating the outline onto the image of the golfer,as shown in FIG. 9C, without adjusting the camera height.

In one embodiment, a light calibration is performed to improve lightingconditions based on the brightness and gray properties of known colorpatterns of the marker attachment, for example.

Other steps may be included in the setup and calibration of the systemfor a particular users preferences. For example the golfer may select aspecific golf course to play, a specific voice and appearance of aninstructor and many other customizable features of the system that havenow become apparent to a practitioner in the field based on thedescription and the examples provided.

1. A device for a golfer to practice golf swing mechanics with a golfclub, the device comprising: a computer; and a camera coupled to thecomputer such that the computer is capable of capturing video framesfrom the camera of an image of the golfer and at least a portion of theclub, such that when the golfer swings the club at the golfer's ownpace, the computer matches at least one key part of the image to a knownstandard, the computer determines a club position from the at least onekey part of the image, and the computer provides feedback to the golferbased on a divergence of the position of the club of the golfer from theposition of the club of the known standard.
 2. The device of claim 1,wherein the camera is positioned face on to the golfer, and the computermeasures a parameter related to a length of the club and compares themeasured parameter related to the length to a known standard length forat least one position of the club.
 3. The device of claim 2, furthercomprising a marker attachment having a spacer member with a firstmarker at one end of the spacer member and a second marker at anopposite end of the spacer member, wherein the computer determines thelength of the marker attachment by determining the distance between thefirst marker and the second marker.
 4. The device of claim 3, whereinthe distance is measured in pixels.
 5. The device of claim 3, whereinthe computer compares the length of the marker attachment to the knownstandard length for a plurality of club positions.
 6. The device ofclaim 5, wherein the plurality of club positions is at least thirty clubpositions per second.
 7. The device of claim 5, wherein the plurality ofclub positions is at least sixty club positions per second.
 8. Thedevice of claim 3, wherein the marker attachment has a plurality ofmarkers and at least one of the markers comprises an orb, and the orbhas at least two colors such that the computer is capable of determiningrotation of the marker attachment from the changing fraction of the atleast two colors that are visible in the image.
 9. The device of claim8, wherein the rotation of the marker attachment is used to determinedivergence from a known standard.
 10. The device of claim 9, wherein thedivergence is used to calculate the effect on a trajectory of a ball ina golf simulator.
 11. The device of claim 10, further comprising a balllaunch monitor, wherein the launch monitor is capable of determining thespeed and direction of a ball after impact with a head of the club, andthe computer determines the trajectory of ball in a golf simulator basedon the speed and direction of the ball and the rotation of the shaft ofthe club.
 12. The device of claim 10, wherein the computer is capable ofproviding an instant replay that instructs the golfer how to correctimproper golf swing mechanics to improve the trajectory of the golfball.
 13. The device of claim 1, wherein the camera is positioneddownline of the golfer, and the computer measures a parameter related toan angle of a shaft of the club and compares the measured parameterrelated to the angle to a known standard angle for at least one positionof the club.
 14. The device of claim 13, wherein the at least one keypart includes the point where a grip of the club intersects the shaft ofthe club.
 15. The device of claim 14, wherein the point where the gripintersects the shaft is marked by a first marker.
 16. The device ofclaim 15, wherein the first marker is attached at one end of a spacermember having a second marker attached at an opposite end.
 17. Thedevice of claim 16, wherein the marker attachment has a plurality ofmarkers and at least one of the markers comprises an orb, and the orbhas at least two colors such that the computer is capable of determiningrotation of the shaft from the changing fraction of the at least twocolors that are visible in the image during rotation of the shaft of theclub.
 18. The device of claim 17, wherein the rotation of the shaft isused to determine divergence from rotation of a known standard forrotation of the shaft of the club.
 19. The device of claim 18, whereinthe divergence is used to calculate the effect on a trajectory of theball in a golf simulator.
 20. The device of claim 14, wherein a rotationof the shaft of the club is determined from the image of a head of theclub.
 21. The device of claim 20, further comprising a ball launchmonitor, wherein the launch monitor is capable of determining the speedand direction of the ball after impact with a head of the club, and thecomputer determines the trajectory of the ball in a golf simulator basedon the speed and direction of the ball and the rotation of the shaft ofthe club.
 22. An interactive method of tracking and analyzing golf swingmechanics of a golfer using a golf club, the method comprising: viewingthe golfer with a video camera; coupling the video camera to a computersuch that the computer is capable of capturing images from the videocamera; determining a key part from the images; tracking the position ofthe golf club during a swing using the key part; comparing the positionof the golf swing to a reference position of a known standard swing;providing feedback to the golfer such that the golfer is capable ofimproving the swing mechanics.
 23. The method of claim 22, wherein thestep of providing feedback includes providing visual feedback or audiblefeedback or both visual feedback and audible feedback.
 24. The method ofclaim 23, wherein the visual feedback includes: superimposing a patternof a golfer having a known standard golf swing mechanics over the imageof the golfer on a display screen based on the key position identifiedby the computer from the image.
 25. The method of claim 24, wherein theaudible feedback is capable of instructing the golfer about at least oneimproper aspect of swing mechanics in real time during a swing by thegolfer.
 26. The method of claim 25, wherein the audible feedback iscapable of informing the golfer of a flat back swing based on imageanalysis of the image by the computer.
 27. The method of claim 23,wherein the step of superimposing includes: advancing the image from oneframe to the next in real time and superimposing the pattern of thegolfer having a known standard golf swing mechanics to each of aplurality of sequential images of the golfer in each frame based on thekey position identified by the computer from the image.
 28. The methodof claim 27, further comprising: attaching a marker attachment on ashaft of the club of the golfer.
 29. The method of claim 28, furthercomprising: exhibiting a surface of the marker attachment having a colorpattern thereon; analyzing the color pattern; comparing the colorpattern of the marker of the golfer to the color pattern of a knownstandard golfer; determining divergence from the color pattern of theknown standard golfer; and providing the golfer feedback concerning thedivergence.
 30. The method of claim 29, wherein the feedback is audible.31. The method of claim 29, wherein the feedback is capable of informingthe golfer of a slice or a hook.
 32. The method of claim 31, wherein thefeedback is a golf simulator capable of showing the trajectory of thegolf ball of the golfer compared to the trajectory of the golf ball ofthe known standard golfer.
 33. The method of claim 32, wherein thefeedback includes an explanation of the defect in golf mechanics of thegolfer and providing drills to practice correcting of the defect in golfmechanics.
 34. The method of claim 33, wherein the feedback includesrepeating the shot and showing a comparison of the original trajectory,the repeated trajectory and the known standard trajectory.
 35. Themethod of claim 22, wherein the step of determining a key part from theimages includes determining the coordinates of a first marker attachedto a shaft of the club at the intersection of a grip and a shaft of theclub.
 36. The method of claim 35, wherein the step of tracking theposition of the golf club includes determining the position of at leastone additional marker spaced at known distance from the first marker,determining a linear fit from the first marker through the at least oneadditional marker, wherein an angle from a fixed direction from thefirst marker to the line of the linear fit is capable of beingdetermined.
 37. The method of claim 36, wherein the step of tracking theposition of the golf club further comprises counting the number ofpixels from the first marker to the at least one additional marker. 38.The method of claim 37, wherein the step of tracking the position of thegolf club further comprises counting the number of pixels from a centerof mass of the body to the position of the first marker.
 39. The methodof claim 38, wherein the step of comparing the position of the golfswing to a reference position of a known standard swing includescomparing at least one of the measurements made in the step of trackingthe position to at least one related value measured from the knownstandard swing at the reference position associated with the actualposition of the first marker of the golfer, the at least one of themeasurements made in the step of tracking the position being selectedfrom the group of measurements consisting of the number of pixels from acenter of mass of the body to the position of the first marker, thenumber of pixels from the first marker to the at least one additionalmarker, the coordinates of the position of the center of mass of thegolfer's head, and the angle from a fixed direction from the firstmarker to the line of the linear fit.
 40. The method of claim 3, whereinthe step of comparing the position of the golf swing to a referenceposition of a known standard swing includes comparing at least two ofthe measurements made in the step of tracking the position to at leasttwo related values measured from the known standard swing at thereference position associated with the actual position of the firstmarker of the golfer.
 41. The method of claim 22, wherein the step ofviewing the golfer views the golfer from a plurality of cameraspositioned for different views of the golfer.
 42. The method of claim22, further comprising a step of analyzing the brightness and grayproperties of known color patterns of a marker attachment and reportinglight conditions to the golfer.
 43. The method of claim 22, furthercomprising a step of disposing the camera a proper distance from thegolfer during setup by comparing the height of the golfer to the heightof a known standard golfer.
 44. The method of claim 22, furthercomprising using a marker attachment as a pointing device to control thecomputer.
 45. The method of claim 44, wherein the step of using a markerattachment includes the step of mirroring the image of the golfer on thedisplay.
 46. The method of claim 22, further comprising: selecting atype of golf club; taking a practice swing with the type of golf club;viewing the practice swing in real-time during the practice swing;replaying the practice swing; and analyzing the practice swingstep-by-step audibly commenting on the swing mechanics during each stephaving comments associated with the step.
 47. The method of claim 22,further comprising: predicting the trajectory of a ball; and determiningfrom the trajectory the lie of the ball in a simulated golf environment.48. The method of claim 47, further comprising: using a launch monitorto determine ball speed and initial direction of the ball when using aputter for long putts, a wedge, an iron, a wood or a driver; attaching amarker having plurality of colors or patterns on the club; predictingthe effect of ball rotation imparted by rotational position of the clubat impact on the trajectory of the ball from image analysis of themarker having a plurality of colors using an image analyzer; and usingthe image analyzer to determine the ball speed and initial direction ofthe ball when using a putter for a short putt, when the image analyzeris capable of improving the accuracy of the simulation of the shortputt.
 49. The method of claim 48, further comprising a step of includinga plurality of players in the golf simulation.
 50. The method of claim49, wherein the plurality of players are disposed in different locationsand are playing over an electronic network.
 51. A simulation system fora player comprising: a device for practicing swing mechanics, the devicecomprising a computer, and a camera coupled to the computer such thatthe computer is capable of capturing video frames from the camera of amarker device on a shaft; the marker device having a plurality of orbs,each having an anti-reflective surface, the plurality of orbs including:a first orb; a second orb disposed at a distance from the first orb; afirst bi-colored orb of a first color and a second color; and a secondbi-colored orb of a second color and a first color; wherein the firstbi-colored orb has the first color on a left half and the second coloron a right half and the second bi-colored orb has the first color on aright half and the second color on a left half such that the color ofthe second bi-colored orb is a mirror image of the color of the firstbi-colored orb, such that, when the player swings the shaft at theplayer's own pace, the system identifies swing mechanics information,including: determining the coordinates of the first orb in relation to acenter of mass of at least a portion of the player; fitting a linear fitfrom the first orb through the second orb, providing an angle of theshaft to a reference direction; measuring the apparent distance betweenthe first orb and the second orb; and measuring a rotation of the shaftbased on a count of the number of pixels of the second color and thethird color for each of the first bi-colored orb and the secondbi-colored orb; and the system compares the swing mechanics informationto a known standard; and provides real-time visual and audible feedbackto the player.
 52. The system of claim 51, wherein the first orb, thesecond orb and the third orb have a third color, and the third color isof a different color than the second color and the third color of thefirst bi-colored orb and the second bi-colored orb.
 53. A markerattachment comprising a plurality of orbs, each of the plurality of orbshaving an anti-reflective surface, the plurality of orbs including: afirst orb having a uniform surface color; a second orb of the same coloras the first orb disposed at a distance from the first orb; a third orbof the same color as the first orb disposed between the first orb andthe second orb; a first bi-colored orb of a second color and a thirdcolor; and a second bi-colored orb of a second color and a third color;wherein the first bi-colored orb has the second color on a left half andthe third color on a right half and the second bi-colored orb has thesecond color on a right half and the third color on a left half suchthat the color of the second bi-colored orb is a mirror image of thecolor of the first bi-colored orb;